SE425381B - SET OF RECOVERY OF NICKEL FROM A USED FAT HEATING CATALYST - Google Patents

Description

eieoeaee _ 2 of organic constituents. It is stated that these problem solutions are based on annealing, grinding of the annealing residue and hydrochemical recycling of the metal. However, these methods are less suitable in practice in that the catalyst support during the annealing forms silicates or other compounds together with the metal, which compounds are very resistant to acids and therefore make the recycling of the metal more difficult and expensive. There is therefore a call for new processes for recycling the catalyst metal, e.g. nickel.

Here, the present invention provides a novel process for economically advantageous recovery of the nickel content of spent catalysts of the preamble of claim 1. This process means that the fat in the catalyst mixture is saponified to a solution of soap mass by adding an alkaline aqueous solution to the fat curing catalyst. The nickel metal and the carrier are then separated from the soap mass solution, after which the nickel metal is leached out of the carrier by means of sulfuric acid, the nickel being recovered in the form of a nickel sulphate solution.

For alkali use, an alkaline hydrogen solution consisting of contaminated alkali hydroxide solution from electrode preparation in the accumulator industry is suitably used. This used and contaminated alkali hydroxide solution is otherwise not used, but is neutralized and emptied into drains after treatment in treatment plants.

The separated solution of soap mass is suitably neutralized and salted out by means of sulfuric acid and a salt solution, and the soap mass is separated from the solution. Senna soap mass can be used for, for example, cleaning purposes in industry. The salting is preferably used in a salt solution which consists of a waste solution purified from heavy metals by ion exchange from nickel pulp production in the accumulator industry and which mainly contains sodium sulphate dissolved in water. This solution is also a pure waste product, which is normally emptied into drains.

From the recovered nickel sulphate solution, nickel or nickel compounds can be obtained. A suitable use for the nickel sulphate solution is as a starting material for the production of active nickel hydroxide pulp for alkaline, electric accumulators. Further information on how such pulp production can be carried out can be found, for example, in Swedish patent 324 39l. The invention will now be described in more detail with reference to the accompanying flow chart.

The spent fat curing catalyst is placed in a heated reaction vessel equipped with a stirrer. An aqueous aqueous solution is prepared, which may consist of potassium hydroxide or sodium hydroxide in solution, the fat content of the catalyst mixture being doubled to a maximum of two masses. As previously mentioned, a spent alkali hydroxide solution from electrode preparation in the accumulator industry is suitably used for desalination. Since this solution is usually not neutralized and destroyed, this process chemical is practically free. The impurities present in the solution are not of such a nature as to affect the nickel recovery from the fat curing catalyst.

In a filter or a centrifuge, the uppercut two-mass mass is separated from the reaction vessel from the still solid non-volatile particles, which form a residue of finely divided nickel metal and carrier. This residue is washed with water and concentrated in water in a reaction vessel, where nickel is leached by sulfuric acid with stirring and heating to about 90 DEG-90 DEGC.

Uriakning can possibly for better nickie exchange take place in several steps.

Nickiet, now dissolved in an aqueous solution of nickel sulfate, is separated from a filter by a filter. The carrier is washed and can then be reused. Suitable use for the carrier is, for example, as a filter aid in the recycling of nickel and cadmium from scrap or manufacturing equipment in the aluminum battery industry.

The obtained nickel sulfate solution can be used for the production of metallic nickel, for example for recycling into catalysts.

It can also be advantageously used as a starting material for the production of nickel hydroxide mass for alkaline accumulators. Swedish patent 324 391 describes how continuous precipitation is produced by continuous precipitation based on nickel sulphate, but also how the same production can take place with an older, batch process.

The diluted and filtered fat solution is collected in a reaction vessel, where it is neutralized by the addition of sulfuric acid and is additionally added with a solution for the release and precipitation of two-mass.

The salt solution may suitably be a waste solution from pulp production in the accumulator industry, which has been purified from heavy metals by means of ion exchangers. The solution contains mainly neutral sodium sulphate. Since this solution can not normally be reused in accumulator manufacturing, this process chemical is also available virtually free of charge.

The formed soap mass is separated and can then be used for cleaning purposes. The filtrate contains mainly alkali sulphates and can be drained into drains after possible purification.

As shown, the process can be performed with very simple and inexpensive chemicals.

If waste solutions from the accumulator industry are used, as described above, only fresh sulfuric acid needs to be added. In addition to the recycling of nickel, it is also possible to assimilate the other components of the original, spent catalyst mixture. The process can therefore be carried out at low cost. It also solves a troublesome environmental problem in that the spent catalyst mixtures can be rendered harmless in a sensible way.

Example: To test the effectiveness of the process, a sample of a spent nickel catalyst mixture was heated together with a waste solution of potassium hydroxide of spec weight 1,17 to 7006. The sample composition was about 25% nickel, about 10% kieselguhr and about 65% fat. When the fat in the sample was saponified, it was filtered, obtaining a filter cake of nickel and kieselguhr and a filter consisting of soap solution.

The filter cake was washed and slurried with a little water. The filter cake was then leached with dilute sulfuric acid at a temperature of 7G ° C. The acid consumption was measured at 0.4 l conc. sulfuric acid per kg filter cake.

The solution was filtered and the recovered nickel was determined to be 95.4% of the nickel content of the original sample. The soap solution was added with 5% sulfuric acid, precipitating soap flakes. The acid consumption was 2 liters of 5% acid per kg of the original sample. The solution was filtered, leaving soap as a filter cake.

Claims (5)

CLAIMS 1. Methods for recovering nickel from a spent fat hardening catalyst consisting of finely divided nickel metal on a support of, for example, diatomaceous earth and / or a synthetic material and suspended in fat, characterized in that the fat is diluted to a solution of soap mass by adding an alkaline aqueous solution to the grease curing catalyst, and then separating the nickel metal and the support from the solution of soap mass, after which the nickel metal is leached from the support by means of sulfuric acid, whereby nickel is recovered in the form of nickel sulphate solution. 2. A method according to claim 1, characterized in that an alkaline aqueous solution consisting of contaminated alkali hydroxide solution from the preparation of electrodes in the accumulator industry is used for the saponification. 3. A method according to claim 1, characterized in that the separated solution of soap mass is neutralized and salted out by means of sulfuric acid and a salt solution and the soap mass is separated from the solution. 4. A method according to claim 3, characterized in that a saline solution is used which consists of heavy metal by ion exchange purified waste solution from nickel mass production in the accumulator industry and which mainly contains sodium sulphate dissolved in water. 5. A method according to claim 1, characterized in that the recovered nickel sulphate solution is used for the manufacture of active nickel hydroxide pulp for alkaline electric accumulators.